The present invention relates to an induction device.
Japanese Utility Model Publication H06-9111 discloses a transformer that includes a printed-circuit board, a coil formed by a conductive pattern on the printed-circuit board, a subsidiary board disposed above the coil on the printed-circuit board and another coil formed by a conductive pattern on the subsidiary board. A pair of upper and lower cores are fixed to the printed-circuit board in such a way that the cores face each other and hold therebetween the printed-circuit board and the subsidiary board in the region of the coil.
In the above structure wherein the cores are fixed directly to the printed-circuit board, there is a fear that the cores and the printed-circuit board may be broken by heat stress generated by the difference of thermal expansion coefficient between the cores and the printed-circuit board. The present invention is directed to providing an induction device having cores and a coil retainer that are hardly susceptible to the heat stress generated by the difference of the thermal expansion coefficient between the cores and the coil retainer.